A disk drive can include a disk upon which data can be stored. The disk drive may store certain critical data on the disk, which may be used for an operation of the disk drive. The critical data may be kept in a reserved area on the disk.
However, due to dynamic random-access memory (“DRAM”) corruption, disk drive defects, shock or vibration events, power surges, power cuts, or other events, the critical data may become corrupted. Thus, a spare copy of the critical data may be used and stored in a separate location. However, the spare copy of the critical data may also become corrupted at the same time as the critical data.
For example, when the critical data becomes corrupted and the disk drive enters a hang state, a write buffer could become corrupted. Thus, the spare copy of the critical data may be overwritten with a copy of the corrupted critical data. In such a case, all valid versions of the critical data may be lost. In some instances this could cause a disk failure in the disk drive. If the critical data was being used on power up, the disk drive could also enter an irrecoverable stage.